In a large skillet, over medium heat, cook sausage; stirring often; 7 minutes or until browned.
Remove sausage; drain and pat dry with paper towels.
In a stainless-steel Dutch oven, over medium heat, heat oil gradually; whisk in flour, and cook, whisking constantly, 18 to 20 minutes or until flour is caramel-colored; do not burn mixture.
Reduce heat to low, and cook, whisking constantly, until mixture is milk chocolate-colored and texture is smooth; about 2 minutes.
Increase heat to medium; stir in onion and next 4 ingredients, and, if desired, ground red pepper; cook, stirring constantly; 3 minutes.
Gradually stir in chicken broth; add chicken and sausage.
Increase heat to medium-high; bring to a boil.
Reduce heat to low, and simmer, stirring occasionally; 1 hour and 30 minutes to 1 hour and 40 minutes or until chicken is done.
Using 2 forks, shred chicken into large pieces
If you took chicken out of the pot to shred, add back to mixture
Stir in shrimp and cook 5 minutes or until shrimp turn pink
Serve immediately with desired toppings.